Authors

Date of Completion

Keywords

Degree

Ph.D.

Abstract

Exercise-induced muscle damage is associated with inflammatory and regenerative phases that are modulated by the interaction between inflammatory cytokines (namely IL-1β, IL-6, TNF-α), growth factors (IGF-I, IGFBP-1, IGFBP-3), and anabolic hormones (GH, testosterone). Administration of NSAID and opioids is a common practice following muscular injury. While this practice is believed to be an adjunct to the healing process it may be detrimental to muscle regeneration through alterations in the inflammatory and endocrine responses. Therefore, the purpose of this investigation was twofold: (1) to observe the responses of circulating IL-1β, IL-6, TNF-α, IGF-I, IGFBP-1, IGFBP-3, GH, and testosterone following eccentric exercise-induced muscle damage (EX), and (2) to investigate the effects of ibuprofen and vicoprofen on these circulating factors following EX. Forty-two male subjects performed 100 eccentric contractions (10 sets of 10 repetitions) of the dominant quadriceps muscle group using 120% of their 1RM on an isotonic leg extension machine. Blood samples were measured immediately before (Pre), midway through (Mid), immediately following (IP), 15min, 30min, 1h, 2h, 4h, 6h, 24h, 48h, 72h, 96h, and 120h following EX. Subjects were randomly placed in either group: (a) placebo, (b) vicoprofen, or (c) ibuprofen, in a double blind manner. Following EX, significant increases were observed for circulating concentrations of GH (266%, at IP, p < .003), IGFBP-1 (40% at 24 h, p < .0002), and IL-6 (78% at 6 h, p < .0000) as compared to resting values. The vicoprofen group demonstrated significantly higher and lower concentrations of IGFBP-1 and testosterone, respectively, by day 5 as compared to the placebo group (IGFBP-1, p < .03; testosterone, p < .04) and the ibuprofen group (IGFBP-1, p < .05; testosterone, p < .05). The most significant finding from this study was the increased serum IGFBP-1 concentration 24 hours after EX. These data suggest that the primary response following exercise-induced muscle damage is catabolic in nature. While this response appears to be detrimental to the myoregenerative process, it may be required for complete muscle fiber regeneration. The drug intervention data indicated that vicoprofen administration induced a catabolic state during the 5d recovery period from EX. These results suggest that opioids; may interfere with normal muscle regeneration following exercise-induced muscle damage through alterations in the endocrine and inflammatory responses. ^